Analysis Of Sealing Property And The Effect Factors About Torpedo Stern Shaft’s Mechanical Seal

In order to prevent sea water from damaging the torpedo structure, and ensure the realization of torpedo combat mission, the torpedo tail shaft seal as a high hydrodynamic pressure motive seal plays an important role. Because the torpedo tail structure design space is limited, the structure design is more difficult. At present, the domestic 80%-90% sealing technology is the mechanical seal, the analysis of the torpedo tail shaft seal performance is less in view of the influence of the factors such as the roughness of the friction pair, the pressure of the spring, the pressure of the sea water and the rotating speed of the tail shaft.Mechanical seal performance is closely related to the seal face morphology. Considering the self-imitation and self-similarity of the surface topography, this paper makes a comparison of rough degree and fractal dimension with describing the characterization of sealing surface topography, and made use of the Structure function method to gain the correspondence between roughness and fractal dimension under different conditions; Then, the leakage rate of the seal is obtained by using the Navier-Stokes equation in allusion to the mixed friction state; At the same time, the real contact area of the sealing surface and the Hole distribution area were obtained by using the W-B model of the fractal theory; Thereby, the leakage model of stern shaft mechanical seal was established based on the fractal theory. Finally, the leakage model was modified by taking into account the beating and seal face wear factors, and verified by the test of the mechanical seal of stern shaft.According to the model, this paper analyzed the influence on tail shaft mechanical seal leakage of fractal dimension, spring pressure, and sea water pressure etc, and concluded that the selection of various parameters can meet the requirements of sealing performance specification. At the same time, the optimization of the fractal dimension, the spring pressure, the seal face width was carried out for further engineering design.In this paper, the different parameters of the shaft seal and trials were designed to verify the influence of this design parameters on the sealing performance. Finally, it’s concluded that the theoretical model had a certain degree of application value in practical engineering by comparing the results of torpedo test and theoretical analysis.